The Journal of Adhesive Dentistry, 02/2007

Purpose: The purpose of this study was to examine the sensitivity of the microtensile bond strength (µTBS) to changes in the specimen design using three different dentin bonding systems, utilizing both experimental and finite element analysis (FEA). Materials and Methods: Freshly extracted bovine central incisors were randomly divided into 9 experimental groups. Flat dentin surfaces were exposed and polished with 600-grit SiC papers. The dentin bonding agents (DBA) Adper Prompt L-Pop, Adper Scotchbond 1XT, and Adper Scotchbond Multi-Purpose Plus were bonded to the dentin surface. A 5- to 6- mm-thick layer of resin composite Filtek Supreme was built up incrementally. For each DBA, after 24 h in water, the bonded specimens were sectioned vertically into slabs of stick-, dumbbell- and hourglass-shaped specimens (n = 30). The µTBS test was performed at a crosshead speed of 0.5 mm/min and the fracture surfaces were examined under optical microscopy and SEM. FEA models of the three designs were developed using the TOMECH program and viewed using FEMSYS visualization software. Results: One-way ANOVA, Tukey's and Kaplan-Meier tests revealed no significant differences between the bond strengths for the three designs for the same dentin bonding agent (p > 0.05). However, there were significant differences between the three adhesive systems when using one specimen design. FEA results showed no major differences between the three designs in the maximum stress within the adhesive layer, although the stress distributions for the hourglass shape followed a different pattern. Conclusions: The three different specimen designs had no influence on the bond strength to dentin within one adhesive system. FEA predictions are consistent with the results of the experiments. Keywords: microtensile bond strength, specimen design, FEA, dentin bonding agents

Purpose: To investigate whether application of three all-in-one self-etching adhesives in a phase-separated stage has an adverse effect on bonding to enamel and dentin. Materials and Methods: The shear bond strengths (SBSs) on ground enamel and dentin of the adhesives G-Bond, Hybrid Bond, and iBond, combined with Venus composite, were determined. The adhesives were dispensed in a dish and applied either 1) immediately, 2) after 2 min, or 3) after 5 min dark storage under ambient conditions. The adhesives were shortly stirred with a microbrush and applied. Prior to light activation, the adhesives were air dried for 10 s with a strong air blast. Composite cylinders were produced in a cylindrical mold clamped on the treated surface. SBSs (n = 8) were determined in a universal testing machine at 1 mm/min crosshead speed after 24 h storage in 37°C water. Data were statistically analyzed with Kruskal-Wallis ANOVA and the Mann-Whitney U-Test (p < 0.05). The qualitative compositions of the separated phases were determined by FTIR spectroscopy. Results: In the separated stage, the adhesives showed acidic monomer-rich phases, containing all components of the original adhesive composition, and water-rich phases with minor amounts of mainly functional monomers dissolved. The SBSs of the individual adhesives applied on enamel or dentin at the different times after dispensing were not significantly different. Conclusion: Application of the adhesives tested either as homogeneous solution or in a phase-separated stage has no adverse effect on bonding strength to enamel or dentin when applied under the present study conditions. Keywords: self-etching adhesives, enamel-dentin bonding, phase separation

Purpose: The aim of this in vitro study was to evaluate the effect of two fibers (polyethylene or glass) and a flowable resin liner on microleakage in Class II adhesive restorations. Materials and Methods: Class II adhesive cavities were prepared on mesial and distal surfaces of 40 extracted sound human molars. The cavity margins were below or above the CEJ. The teeth were randomly divided into four groups according to the restoration technique: group 1: restored with a resin composite (AP-X, Kuraray) in bulk after SE Bond (Kuraray) treatment; group 2: flowable resin liner (Protect Liner F, Kuraray) was used before composite restoration; in group 3, a polyethylene fiber (Ribbond) and in group 4, a glass fiber (everStick NET, StickTech) was placed into the bed of flowable resin before composite restoration. Samples were finished, stored in distilled water for 7 days at room temperature, and then thermocycled for 300 cycles between 5°C and 55°C. After sealing the apices, the teeth were varnished within 1 mm of the margins and placed in 0.5% basic fuchsin dye for 24 h at 37°C. After rinsing, the teeth were sectioned longitudinally through the restorations and microleakage was evaluated with a stereomicroscope. Marginal penetration was scored on a 0 to 4 scale, and the data were statistically analyzed using Kruskal-Wallis and the Mann-Whitney U-test. Results: Flowable resin, everStick NET, and Ribbond THM used in combination with flowable resin significantly reduced leakage at occlusal margins in cavities with enamel margins (p < 0.05). When the leakage values on cervical dentin margins were evaluated, there was no statistically significant difference among the tested groups (p > 0.05). Conclusion: Use of flowable composite alone or in combination with polyethylene or glass fibers reduces occlusal leakage in Class II adhesive cavities with enamel margins. Keywords: flowable composite resins, fiber-reinforced composite, microleakage, cavity lining

Purpose: The aim of this in vitro study was to comparatively evaluate the influence of three different light curing units (QTH Hilux, LED SmartLite, PAC Plasmaster) on shear bond strength of an adhesive system (Clearfil SE Bond ) after bleaching. Materials and Methods: Sixty molars were used for this study. Carbamide peroxide was applied to the floor and wall of the dentin surfaces in bleached groups for 3 weeks. Each week the paste was renewed for the bleached group. Teeth were sectioned mesiodistally. The roots of the sectioned teeth were mounted in a cylindrical mold using chemically cured acrylic resin. Composite resin was added to the center of flattened dentin surfaces with an internal diameter of 3 mm and height of 3 mm. The bonding procedure was performed in the bleached test groups as follows: G1: immediately/ QTH; G2: after 1 week/QTH; G3: after 2 weeks/QTH; G4: immediately/LED; G5: after 1 week/LED; G6: after 2 weeks/LED; G7: immediately/PAC; G8: after 1 week/PAC; G9: after 2 weeks/ PAC. The non-bleached groups (control group) were G10: QTH; G11: LED; G12: PAC. Specimens were mounted in a universal testing machine and shear load was applied at a crosshead speed of 1 mm/min until failure. Bond strength values were calculated as MPa and the comparisons were made statistically using one-way ANOVA with light source and bleaching treatment) as the two factors. Results: The mean values of shear bond strength in MPa were: G1 (12.23), G2 (19.18), G3 (23.08), G4 (13.07), G5 (21.01), G6 (25.27), G7 (12.55), G8 (19.06), G9 (25.41), G10 (24.54), G11 (26.99), G12 (25.97). No statistical difference was found between the control group and groups bonded two weeks later. The bond strength values of the control group and those bonded 2 weeks later were higher than other groups. Statistically significant differences were found between the immediate and 1-week groups (p < 0.01). Immediately bonded groups had the lowest bond strength compared to the others (p < 0.05). No significant differences in bond strength were observed among three lightcuring units (p > 0.05). Conclusion: It was concluded that different light-curing units had no effect on shear bond strength of bleached dentin. A 2-week delay in restoration after bleaching improved the reduced bond strength of resin composite. Keywords: bleaching, bond strength, dentin bonding, light-curing units

Purpose: The aim of this study was to determine the influence of four flowable composite linings on marginal microleakage and internal voids in Class II composite restorations with the margins above the cementoenamel junction (CEJ). Materials and Methods: Class II cavities were randomly divided into 8 groups (n = 10). Group 1: One Step Plus/Aelite LS Packable; group 2: One Step Plus/Aelite Flow/Aelite LS Packable; group 3: Comfort Bond/Solitaire 2; group 4: Comfort Bond/Flowline/Solitaire 2; group 5: Solobond M/Grandio; group 6: Solobond M/Grandio Flow/Grandio; group 7: Admira Bond/Admira; Group 8: Admira bond/Admira Flow/Admira. After restoration, all teeth were stored for 24 h, thermocycled (at 5°C to 55°C) 500 times, and soaked in 0.5% basic fuchsin dye for 24 h. After soaking, the teeth were sectioned and observed under a stereomicroscope. Gingival marginal microleakage and internal voids (at the gingival wall interface and in the cervical and the occlusal parts) were recorded. Data were analyzed with the Mann-Whitney U- and Kruskal-Wallis tests (p < 0.05). Results: Statistical analyses indicated that the use of flowable resin composites provided a reduction in microleakage in groups 6 and 8. Groups 2 and 4 showed fewer voids in the cervical area than without flowable composites. Conclusion: It was concluded that none of the materials tested was able to eliminate the marginal microleakage on the cervical wall. Flowable resin composites under nanohybrid (group 6) and ormocer (group 8) composites provided a significantly different reduction in microleakage compared to restorations without flowable liners. Fewer cervia voids were observed in packable composites with flowable liner (groups 2 and 4) than without flowable liner (groups 1 and 3s). Keywords: composite, microleakage, void, flowable

Purpose: (1) To evaluate the interfacial strength between FRC Postec posts and three luting agents (Multilink, Variolink II, and MultiCore Flow) following different surface treatments, and (2) to observe the effect of sandblasting (Rocatec Pre) on the surface morphology of methacrylate-based fiber posts. Materials and Methods: The posts received one of the following surface treatments: (1) sandblasting, (2) sandblasting + silanization, (3) silanization or (4) no treatment. The three luting agents were bonded to the post and the post-cement bond strength was evaluated with the microtensile test. SEM observation of sandblasted and nontreated posts was performed. Post-cement interfaces were also evaluated. Data were statistically analyzed with two-Way ANOVA with post treatment and luting agent as factors. Tukey's test was applied for post-hoc comparisons. Results: Post treatment and the interaction between type of luting agent and type of post treatment were significant factors for bond strength (p < 0.001). The type of luting agent did not significantly influence bond strength (p = 0.07). Sandblasting + silanization performed better than sandblasting or no treatment (p < 0.001). Silanization resulted in significantly higher bond strengths than no treatment (p = 0.045). No differences were detected between sandblasting + silanization and silanization. SEM observation revealed an increased surface roughness and exposure of fibers in sandblasted posts. Conclusion: Silanization was confirmed to be a reliable method for improving the bond strength of resin luting agents to fiber posts. Bond strength of resin luting agents to fiber posts was not influenced by the type of luting agent. The sandblasting procedure modified the methacrylate-based post surface texture. Keywords: fiber posts, sandblasting, silane, microtensile bond strength

Purpose: This study compared the shear bond strength (SBS) to enamel of rest seats made with a glass-ionomer cement (Fuji IX GP Fast), a resin-modified glass-ionomer cement (Fuji II LC), and a composite resin (Z100 MP) under monotonic and cyclic loading. Materials and Methods: Rest seats were built up onto the lingual surfaces of 80 intact human mandibular incisors. Specimens (n=10) were stored in distilled water at 37°C for 30 days and subjected to shear forces in a universal testing machine (0.5 mm/min) until fracture. The SBS values were calculated (MPa) using the bonding area (9.62 mm2) delimited by adhesive tags. A staircase approach was used to determine the SBS fatigue limit of each material. Specimens were submitted to either 10,000 cycles (5 Hz) or until specimen fracture. A minimum of 15 specimens was tested for each material. Scanning electron microscopy was used to examine the mode of failure. Data were statistically analyzed with one-way ANOVA and Tukey HSD tests (α = 0.05). Results: Z100 MP yielded higher (p < 0.05) SBS (12.25 MPa) than Fuji IX GP Fast (7.21 MPa). No differences were found between Fuji II LC (10.29 MPa) and the other two materials (p > 0.05). Fuji II LC (6.54 MPa) and Z100 MP (6.26 MPa) had a similar SBS limit. Fuji IX GP Fast promoted the lowest (p < 0.05) SBS fatigue limit (2.33 MPa). All samples showed cohesive failure patterns. Conclusion: Fatigue testing can provide a better means of estimating the performance of rest seats made with dental restoratives. Keywords: glass-ionomer cements, composite resins, fatigue, shear bond strength, dental bonding

Purpose: The aim of this study was to evaluate the clinical success potential of two nanocomposites placed in posterior teeth using an antibacterial adhesive system over 18 months. Methods: A total of 49 Class I and 47 Class II restorations were placed in the permanent teeth of thirty adult patients. The carious lesions were restored with Grandio (Voco) or Filtek Supreme (3M ESPE) using a two-step self-etching antibacterial adhesive system Clearfil Protect Bond (Kuraray). The restorations were finished with fine-grit diamond burs, Enhance polishing system, and Sof-Lex finishing brushes. The restorations were evaluated at baseline, 6, 12, and 18 months after placement using modified Ryge criteria for color stability, marginal discoloration, marginal adaptation, caries formation, anatomic form, postoperative sensitivity, surface roughness, and retention. Results: The changes in the parameters were assessed using the Cochran Q test and the McNemar test at a significance level of p < 0.05. All restorations were classified as clinically satisfactory after 18 months. Statistical analysis demonstrated differences only in superficial roughness, with Grandio exhibiting more surface roughness than Filtek Supreme (p < 0.05). Conclusion: Posterior restorations built up with the novel nanocomposites using an antibacterial self-etching system showed satisfactory results at the 18-month recall appointment relative to all criteria except the surface texture in the case of Grandio. Further evaluations are necessary for a more in-depth analysis. Keywords: nanofill, nanohybrid, antibacterial adhesive, posterior restorations

This article describes how dental adhesives evolved from the cements developed by the Mayan Indians into today's modern dental adhesives. Particular attention is paid to Oskar Hagger, a chemist who worked for DeTrey/Amalgamated Dental Company, and already in 1949 developed an adhesive product called Sevriton Cavity Seal. That adhesive was acidic and interacted with the tooth surface on a molecular level. His ground-breaking concept makes him the true "Father of Modern Dental Adhesives." Hagger's concept was soon adopted by other investigators, and different generations of dental adhesives evolved thereafter. Today, after many years of accepting that the key to the success of dental adhesives is the micromechanical retention resulting from acid etching of dentin and enamel, we still return to Dr. Hagger's original concept that bonding can be achieved via molecular interactions between adhesives and tooth surfaces. That concept is obvious in the development of newer generations of dentin adhesives. These adhesives, like Sevriton Cavity Seal, rely on acidic monomers capable of etching and interacting on a molecular level with tooth surfaces in order to form physical/chemical bonds between the restoration and the tooth. Whether Hagger's concept will become the norm in the future is still an open question, but one thing is certain: Hagger's idea is still very much alive. Keywords: review, generations, clinical evaluations

Purpose: To evaluate and compare the marginal integrity of in vitro Class V restorations made with all-in-one adhesive systems by thermocycling after different periods of water storage, to provide an analysis of static and quasi-dynamic deterioration in water. Materials and Methods: Standardized Class V cavities (17 groups, 8 specimens each) were prepared in extracted human caries-free anterior teeth. The cavities were filled using 14 all-in-one adhesive systems/composite resin combinations in addition to the multi-bottle adhesive systems Syntac and OptiBond FL (etch-and-rinse technique) and Clearfil SE Bond (self-etching) as controls. The samples were thermocycled after water storage for 21 days, after 1 year and again after 3 years (2000 cycles between 5 and 55°C) and replicas were made before and after each thermocycling treatment (TC) for quantitative marginal analysis in the SEM. Results: In dentin, marginal adaptation showed no significant differences between all groups after the first TC. After one year of water storage and a second TC, the results for Prompt L-Pop (1999), Adper Prompt L-Pop/Tetric Ceram, and One-up Bond F Plus showed a statistically significant decrease of margin quality 1 (MQ1) score compared to the reference groups. When the all-in-one adhesives G-Bond, AQ-Bond, Hybrid Bond, and One-up Bond F Plus were used, the enamel margins of restorations showed lower percentages of "continuous margins" (p < 0.05) after 1 year of water storage and TC. Of the materials tested after 3 years of water storage and TC, only AQ Bond had a significantly lower MQ1 score. Conclusion: While all materials exhibited deterioration in the MQ1 quality score, the rate of deterioration varied, and the results show that different materials have different deterioration rates after initial vs long-term water storage. The deterioration along margins in dentin was not as extensive as predicted from other studies; however, the results from the enamel margins show that one-bottle all-in-one adhesives seem to be significantly affected by water storage. The results of this study suggest that the all-in-one adhesive group members perform very differently from each other: thus, data need to be explored further at the level of each different adhesive product. Keywords: marginal quality evaluation, in vitro Class V restorations, adhesive system effectiveness

Purpose: The aim of this study was to evaluate the clinical retention to dentin of a single-step self-etching adhesive system. Materials and Methods: A total of 133 Class V restorations were placed with the self-etching primer Xeno III and a resin composite (Tetric Ceram) or a polyacid-modified resin composite (Dyract AP) in noncarious cervical lesions without intentional enamel involvement. The restorations were evaluated at baseline and then every 6 months during a 2- year follow-up. Dentin bonding efficacy was determined by the percentage of lost restorations. Results: During the 2 years, 130 restorations could be evaluated. The cumulative loss rate at 2 years was 7.7%, with no significant differences between the two restorative materials. The self-etching adhesive fulfilled the 18-month full acceptance ADA criteria. Conclusion: The single-step self-etching adhesive showed acceptable clinical retention rates to dentin surfaces during the evaluation period independent of restorative material used. Keywords: adhesion, clinical, cervical, dental material, etch, resin, restoration, self-etching

Purpose: The purpose of this study was to evaluate the shear bond strength of composite to dentin and enamel using the new etch-and-rinse adhesive XP Bond compared to other adhesives (OptiBond Solo Plus, Adper Scotchbond 1 XT, Syntac Classic). Materials and Methods: Shear bond strength (MPa) was measured by shearing a resin cylinder 4.5 mm in diameter from prepared buccal surfaces of human third molars using an Instron Testing Machine equipped with a chiselshaped rod. In addition, micro-Raman spectroscopy was performed to determine if there was a chemical interaction between the resin adhesive and dentin and enamel. Results: Significant differences were observed among the dentin and enamel values generated with the adhesives tested. XP Bond generated statistically similar values to Optibond Solo Plus and Adper Scotchbond 1 XT to both enamel and dentin. Syntac Classic generated significantly lower values to both enamel and dentin. Conclusion: Micro-Raman spectroscopy showed a complete infiltration of resin into the demineralized dentin zone. In addition, it strongly suggested a chemical interaction with XP Bond and components of dentin. It is hypothesized that this interaction is due to the formation of calcium phosphate complexes derived from mineral apatite in the dentin and phosphate esters in the adhesive. Keywords: adhesion, bonding, chemical analysis, Raman spectroscopy

Purpose: The objective of the present study was to determine the fatigue resistance of several contemporary dentin adhesives as well as a resin-modified glass-ionomer cement. Materials and Methods: Cyclic loading of the adhesive interface was achieved by a microshear fatigue setup following a staircase approach, where the stress level at which 50% of the specimens fail after 104 cycles was calculated as the median microshear fatigue resistance (µSFR). Results: For all products tested, the µSFR was lower than the microshear strength. A wide spread in µSFR was observed, ranging from 24% to 76% of the quasi-static microshear strength, irrespective of the type of adhesive used. Conclusion: The results of this study show that the microshear test setup is a discriminative and reproducible way of testing tooth/adhesive interfaces, even at relatively low stresses. The results clearly indicate that such interfaces are vulnerable to progressive damage by cyclic loads. Further, at present there is not one bonding approach, whether "total etch" or "self-etching", that consistently yields higher fatigue resistance: the product factor seems to be of primary importance. Keywords: fatigue, dental adhesive, dynamic testing

Purpose: To evaluate the sealing ability of etch-and-rinse and self-etching adhesives in Class V cavities before and after thermocycling in vitro. Materials and Methods: Etch-and-rinse adhesives (Prime & Bond NT [P&B], XP Bond [XPB], Scotchbond 1 XT [SBX], Syntac [SYN]) and self-etching adhesives (Xeno III [XNO], i-Bond [IBO], Clearfil SE Bond [CLF]) were used. A microleakage test was performed to evaluate marginal sealing. Seventy molars were divided into seven groups according to the adhesive used. Class V cavities were restored and each group was divided into two subgroups. One group was water immersed for 24 h and the other was thermocycled. Then, specimens were immersed in fuchsin and sectioned. Microleakage and dentin permeability were recorded on occlusal and gingival walls and data were statistically analyzed. Results: Etch-and-rinse adhesives provided perfect occlusal sealing. Self-etching adhesives obtained slight occlusal leakage. In the gingival wall, XNO and CLF showed the lowest leakage, followed by XPB and SBX, then P&B. SYN and IBO exhibited the highest leakage. All SE adhesives and XPB provided sealed dentinal tubules. Thermocycling did not affect the occlusal sealing but reduced the gingival sealing when P&B, SYN, XNO, CLF, and IBO were used. Conclusion: In enamel, marginal leakage was prevented when phosphoric acid was used. Self-etching adhesives promoted slight occlusal leakage. The gingival sealing was poorer than the occlusal sealing. XNO, CLF followed by XPB obtained the best gingival sealing. Thermocycling did not affect the occlusal bonding but reduced the gingival sealing, except when XPB and SBX were used. Keywords: adhesives, Class V sealing, thermocycling, in vitro

Purpose: To determine the microleakage of etch and rinse adhesives. Materials and Methods: Standardized Class II cavities were cut in 40 human molars with one proximal box limited within enamel and one proximal box extending into dentin. Teeth were assigned randomly to 5 groups (n = 8) and restored with incrementally placed composite restorations. Five combinations were tested: G1 = XP Bond + Ceram X Mono, G2 = Syntac Classic + Tetric EvoCeram, G3 = Scotchbond 1 XT + Z250, G4 = P&B NT + Ceram X mono, G5 = Optibond Solo Plus + CeramX Mono. After finishing and polishing, teeth were stored for 48 h in water at 37°C before being subjected to artificial aging by thermal stress (5/55°C, 2000x, 30 s) and mechanical loading (50 N, 50,000x). Teeth were isolated with nail varnish and immersed in 5% methylene blue for 1 h. After sectioning, specimens were evaluated for leakage (ordinal scale: 0 to 4) at enamel and dentin margins under a stereomicroscope. Results were analyzed using the Kruskal-Wallis H-test and Mann-Whitney U-test (p < 0.05). Results: Statistical analysis showed significant differences among the groups in both enamel and dentin. Mean ranks (H-test) were: enamel: G2 (64.44) < G1 (66.69) < G4 (74.88) < G3 (98.25) and G5 (98.25); dentin: G3 (65.53) < G1 (74.42) < G4 (81.09) < G2 (81.84) < G5 (99.61). Conclusion: Microleakage of XP Bond is at the same level as or even better than other etch-and-rinse adhesives. Keywords: Class II restorations, dentin adhesives, composite, microleakage

Purpose: To evaluate the 6-month clinical performance of the etch-and-rinse one-bottle adhesive system XP BOND, used in combination with the composite resin Ceram X duo for the restoration of Class V noncarious cervical lesions (NCCL). Materials and Methods: XP BOND was tested in a total of 40 patients who received two Class V Ceram X duo restorations, Adper Scotchbond 1 XT was used as a control. After cleaning the teeth, the surface of the NCCL was treated using a carbide bur in dentin and a 40-µm diamond bur in enamel with no retentive preparations. The lesions were filled with two increments of Ceram X duo after the application of the respective adhesive by a single operator according to manufacturer's instructions. After 6 months, the retention and the marginal integrity were evaluated. Results: Thirty-eight of 40 patients were evaluated after 6 months by two clinicians according to modified USPHS criteria, and all restorations using XP BOND were still in place. In the control group (using Adper Scotchbond 1XT), one restoration was lost. The statistical evaluation (chi2 test) showed no significant differences in any of the criteria. No difference of marginal integrity was found between the two adhesive systems. Conclusion: XP BOND meets the ADA success criteria after 6 months. Keywords: clinical study, noncarious cervical lesions, Class V restorations, adhesive systems

Purpose: To evaluate microtensile bond strength to Class I cavity floor dentin beneath adhesive inlays that were luted with different adhesives, temporary cements, cleaning methods, and curing modes. Materials and Methods: Occlusal cavities (4 x 4 mm, depth 3 mm) were prepared in 96 extracted human third molars. One part of the cavities was temporized with different temporary cements, which were removed after one week using three techniques (scaler or air polishing with Prophypearls or ClinPro powder). Direct resin composite inlays (Clearfil AP-X) were then placed with the luting composite Calibra using three adhesives (XP BOND/SCA, Syntac, Opti- Bond FL). Teeth were cut into beams and after 24 h of water storage at 37°C, the sticks were subjected to microtensile bond strength evaluation. Samples were subjected to SEM fractographic analysis of failed interfaces. Results: Contamination with temporary cement reduced dentin bond strengths (p < 0.05). Removing remnants of cements with Prophypearls air polishing resulted in the lowest bond strengths (p < 0.05). Separate light curing of the adhesives did not produce higher dentin bond strengths (p > 0.05). Syntac still worked when Heliobond was omitted (p > 0.05). Immediate dentin sealing prior to temporizing increased internal bond strength (p < 0.05). Conclusion: The dual-cured adhesive provided higher internal bond strengths between adhesive inlays and dentin. Contamination of dentin with temporary cements is a hazard for excellent dentin adhesion of adhesive inlays. Therefore, immediate dentin sealing and resin coating is promising. Keywords: etch-and-rinse, dentin bonding, adhesive inlays, microtensile bond strength

Purpose: To assess the bond strength to dentin of an experimental adhesive and the proprietary resin cement used in different curing modes to lute ceramic disks of different thicknesses. Materials and Methods: Empress II disks (Ivoclar-Vivadent) were luted to dentin using XP BOND (Dentsply [XP]) in combination with the proprietary self-curing activator (SCA) and cement Calibra (Dentsply [C]). Curing of the adhesive was induced either by mixing with the activator (activator, groups 3 to 6) or by light irradiation for 20 s (group 2). The cement was either light cured for 40 s through the ceramic onlay (groups 1 to 5) or cured chemically (groups 6 and 7). Groups 2 and 4 were compared with group 1, in which Prime & Bond NT (Dentsply DeTrey) was tested as control. In groups 3 and 6, 2-mm-thick onlays were luted with XP+SCA, and the cement was light cured for 40 s or autocured for 5 min, respectively. These groups were compared with group 7, in which Syntac (Ivoclar Vivadent) was applied with C and, in order to reproduce the handling procedures of group 6 (although contrary to manufacturer's instructions), no light irradiation was provided for the adhesive or the cement. The influence of onlay thickness (2, 3, 4 mm) on the bond strength developed by XP+SCA/C was assessed by comparing groups 3, 4, 5. In these groups, C was light cured for 40 s through the onlay. Microtensile beams were obtained from the luted teeth. Results: Bond strengths not including pretest failures (in parentheses: value including pretest failures as 0 MPa) were 21.0 (17.5) MPa in group 1, 24.9 (21.2) MPa in group 2, 23.7 (21.3) MPa in group 3, 29.9 (26.7) MPa in group 4, 30.3 (24.6) MPa in group 5, 28.6 (24.6) MPa in group 6, and 17.1 (9.2) MPa in group 7. Statistically significant differences were found between groups 1 and 4, groups 3 and 5, and groups 6 and 7. Conclusion: The bonding potential of XP BOND used with the activator or light cured in combination with Calibra in self- or dual-curing mode outperformed that of a control adhesive-cement system. The bond strength of XP+ SCA + Calibra was not negatively affected by the onlay thickness.

Purpose: The aim of this clinical study was to evaluate the postoperative hypersensitivity of Empress II inlays/onlays luted under clinical conditions with XP BOND in combination with SCA and Calibra cured in self-curing mode. Materials and Methods: Fifty-three restorations were placed in 38 patients in March and April 2006. No patient received more than two restorations. Luting procedures were performed following manufacturers' instructions. The restorations were evaluated after 2 weeks and 6 months for postoperative hypersensitivity, marginal discoloration, marginal integrity, secondary caries, maintenance of interproximal contact, and fracture. Results: At the 2-week recall, the postoperative hypersensitivity was reported in only 10 and after 6 months in only 3 patients. All other parameters showed alpha scores. Conclusion: All the evaluated restorations were in place and acceptable. The postoperative hypersensitivity recorded after using XP BOND and Calibra in self-curing mode was clinically acceptable. Keywords: ceramic crowns, self-curing, clinical trial, bonding